Magnetic resonance signal intensity ratio of gray/white matter in children. Quantitative assessment in developing brain.

Magnetic resonance imaging (MRI) findings in 87 children with various clinical entities were used to determine the signal intensity ratio of gray/white matter in T1- and T2-weighted images using a 1.5 T MR Scanner. Signal intensity ratio changes in both T1- and T2-weighted images correlated well with advancing age (y = 0.9349-0.001575, r = -0.584, P < 0.0001 in T1-weighted images; y = 0.9798 + 0.002854, r = 0.723, P < 0.0001 in T2-weighted images), but the correlation was more linear when we included only normally developed (34) children (y = 0.9689-0.001967, r = -0.654, P < 0.0001 in T1-weighted images; y = 0.9882 + 0.002965, r = 0.747, P < 0.0001 in T2-weighted images). Abnormal ratios were observed in patients with congenital hydrocephalus, inherited metabolic diseases and cerebral palsy. Although the gray/white matter differentiation would not delineate the myelination itself, measurement of the signal intensity ratio of gray/white matter is a practical way to evaluate delayed myelination in a busy MR center.